Question

What percentage of college students own cellular phones? Let p be the proportion of college students who own cellular phones. (a) If no preliminary study is made to estimate p, how large a sample is needed to be 90% sure that a point estimate will be within a distance of 0.02 from p. 4. (a) __________________________ (b) A preliminary study shows that approximately 88% of college students own cellular phones. Answer part (a) using this estimate for p.

Answer 1

a)

here margin of error E =	0.02
for90% CI crtiical Z          =	1.6449
estimated proportion=p=	0.5
required sample size n =	p*(1-p)*(σ/E)2=	1691.00

b)

here margin of error E =	0.02
for90% CI crtiical Z          =	1.6449
estimated proportion=p=	0.88
required sample size n =	p*(1-p)*(σ/E)2=	715.00